The present invention relates to an image recording material capable of forming three-dimensional images raised from sheet.
For forming images having cubic effect on sheet there have widely been used physical methods such as, for example, pressing sheet using a matrix. In addition, there has recently been adopted a method using a thermoexpansive sheet P which, as shown in sectional construction in FIG. 1, comprises a base sheet 1 and a coating layer 2 formed thereon, the coating layer 2 containing thermoexpansive microspheres 3 of a low boiling, vaporizable material each encapsulated in a thermoplastic resin microcapsule (see Japanese Examined Patent Publication No. 35359/84 and Japanese Laid-Open Patent Publication No. 101954/80).
For forming a three-dimensional image using the aforesaid thermoexpansive sheet, first a desired image is formed on the sheet using a material superior in light absorbing characteristic. For example, the image is formed with black toner using a conventional electrophotographic type copying machine. FIG. 2 (a) shows a state wherein images 4 have been formed with black toner on the coating layer 2 of the thermoexpansive sheet P. Then the surface of the sheet P is irradiated with light, with the result that only the image portions 4 formed with black toner are heated selectively due to the difference in light absorbing characteristic, thereby causing the thermoexpansive microspheres 3 to expand. Consequently, the image portions are raised from the sheet surface to form images having cubic effect as shown in FIG. 2 (b).
After formation of such three-dimensional images according to the above conventional method there remains toner images of black or any other deep color on the coating layer of the thermoexpansive sheet. Formation of such toner images is inevitable in the course of making images three-dimensional, but after completion of the three-dimensional image formation, the presence of such toner images is an obstacle when the image surfaces are to be colored. In the use as a braille sheet, moreover, the toner in a molten condition is likely to fall off the sheet during repeated touching and reading and stain fingers.